Based on conversations in issue MobilityData#250 

Modified station_status.json to aggregate the number of available vehicles per vehicle_type and removed the `bike_id`, `is_reserved`, `is_disabled`, `vehicle_type_id` and `current_range_meters` from the feed since they're available in free_bike_status.json. 

Also modified free_bike_status.json to specify the station_id where the vehicle is, in order to provide more details on the vehicle (such as 'current_range_meters'). So the free_bike_status.json could be used for free floating vehicles and docked vehicles as well to provide more information on each of the vehicles.

Fixed a typo (missing quote)

- updated free_bike_status.json description (2 places)
- corrected a typo ("available vehicles")

Updated based on comments from @kanagy
Fixed typo in free_bike_status description, fixed indentation in examples, matched style of vehicle_docks_available in vehicle_types_available.

vehicle_type_id becomes string

Fix typos
Update definition of free_bike_status.json

…ng_plan_id to example